Image forming apparatus

Abstract

An image forming apparatus includes: an image holding member; a charging unit that charges a surface of the image holding member; an electrostatic image forming unit that forms an electrostatic image on the charged surface of the image holding member; a developing unit that houses a toner for electrostatic image development and develops the electrostatic image formed on the surface of the image holding member with the toner to thereby form a toner image; a transfer unit that transfers the toner image formed on the surface of the image holding member onto a surface of a recording medium; a cleaning unit that includes a cleaning blade and cleans the surface of the image holding member; and a fixing unit that fixes the toner image transferred onto the surface of the recording medium. The cleaning blade has a contact portion that contacts the surface of the image holding member, the contact portion having a JIS-A hardness of from 90° to 130° inclusive. The toner for electrostatic image development satisfies the following formulas: ( ln η( T 1 )− ln η( T 2 ))/( T 1− T 2 )≤− 0.14; ( ln η( T 2 )− ln η( T 3 ))/( T 2− T 3 )≥− 0.15; and ( ln η( T 1 )− ln η( T 2 ))/( T 1− T 2 )<( ln η( T 2 )− ln η( T 3 ))/( T 2− T 3 ), wherein η(T 1 ) is the viscosity of the toner at 60° C., η(T 2 ) is the viscosity of the toner at 90° C., and η(T 3 ) is the viscosity of the toner at 130° C.

1 . An image forming apparatus comprising:
 a photoconductor;   a charging roller configured to charge a surface of the photoconductor;   a light source configured to form an electrostatic image on the charged surface of the photoconductor;   a developing device configured to contain a toner for electrostatic image development and configured to develop the electrostatic image formed on the surface of the photoconductor with the toner to thereby form a toner image;   a transfer belt configured to transfer the toner image formed on the surface of the photoconductor onto a surface of a recording medium;   a cleaning unit that includes a cleaning blade,   wherein the cleaning unit is configured to clean the surface of the photoconductor; and   a fixing roller configured to fix the toner image transferred onto the surface of the recording medium,   wherein the cleaning blade has a contact portion configured to contact the surface of the photoconductor, the contact portion having a JIS-A hardness of from 90° to 130° inclusive,   wherein the toner satisfies the following formulas:
   ( ln  η( T 1)− ln  η( T 2))/( T 1− T 2)≤−0.14;
 
   ( ln  η( T 2)− ln  η( T 3))/( T 2− T 3)≥−0.15; and
 
   ( ln  η( T 1)− ln  η( T 2))/( T 1− T 2)<( ln  η( T 2)− ln  η( T 3))/( T 2− T 3), and
 
   wherein η(T 1 ) is the viscosity of the toner at 60° C., η(T 2 ) is the viscosity of the toner at 90° C., and η(T 3 ) is the viscosity of the toner at 130° C.   
     
     
         2 . The image forming apparatus according to  claim 1 , wherein the toner satisfies (ln η(T 0 )−ln η(T 1 ))/(T 0 −T 1 )≥−0.12 and (ln η(T 0 )−ln η(T 1 ))/(T 0 −T 1 )>(ln η(T 1 )−ln η(T 2 ))/(T 1 −T 2 ), wherein η(T 0 ) is the viscosity η of the toner at T 0 =40° C. 
     
     
         3 . The image forming apparatus according to  claim 1 , wherein the toner satisfies the following formula:
   ( ln  η( T 1)− ln  η( T 2))/( T 1− T 2)≤−0.16.
   
     
     
         4 . The image forming apparatus according to  claim 1 , wherein the toner satisfies the following formula:
   ( ln  η( T 2)− ln  η( T 3))/( T 2− T 3)≥−0.13.
   
     
     
         5 . The image forming apparatus according to  claim 1 , wherein the toner contains a release agent, and
 wherein the toner satisfies the following formula:
   1.0<a/b<8.0, 
   wherein a is the number of release agent domains with an aspect ratio of 5 or more in the toner, and b is the number of release agent domains with an aspect ratio of less than 5 in the toner.   
     
     
         6 . The image forming apparatus according to  claim 1 , wherein the toner contains a release agent, and
 wherein the toner satisfies the following formula:
   1.0<c/d<4.0, 
   wherein c is the total cross-sectional area of release agent domains with an aspect ratio of 5 or more in the toner, and d is the total cross-sectional area of release agent domains with an aspect ratio of less than 5 in the toner.   
     
     
         7 . The image forming apparatus according to  claim 1 , wherein the toner has a maximum endothermic peak temperature within the range of 70° C. to 100° C. 
     
     
         8 . The image forming apparatus according to  claim 1 , wherein the toner has a maximum endothermic peak temperature within the range of 75° C. to 95° C. 
     
     
         9 . The image forming apparatus according to  claim 1 , wherein the toner contains a styrene-acrylic resin as a binder resin. 
     
     
         10 . The image forming apparatus according to  claim 1 , wherein the toner contains an amorphous polyester resin as a binder resin. 
     
     
         11 . The image forming apparatus according to  claim 1 , wherein the cleaning blade has a layered structure. 
     
     
         12 . The image forming apparatus according to  claim 11 , wherein the layered structure includes a first layer having a JIS-A hardness of from 90° to 130° inclusive and a second layer having a smaller JIS-A hardness than the first layer. 
     
     
         13 . The image forming apparatus according to  claim 1 , wherein a pressure applied between the cleaning blade and the surface of the photoconductor is from 2.0 g/mm to 3.2 g/mm inclusive. 
     
     
         14 . An image forming apparatus comprising:
 a photoconductor; and   a cleaning unit that includes a cleaning blade,
 wherein the cleaning unit is configured to clean a surface of the photoconductor; 
   wherein the cleaning blade has a contact portion configured to contact the surface of the photoconductor, the contact portion having a JIS-A hardness of from 90° to 130° inclusive,   wherein the toner satisfies the following formulas:
   ( ln  η( T 1)− ln  η( T 2))/( T 1− T 2)≤−0.14;
 
   ( ln  η( T 2)− ln  η( T 3))/( T 2− T 3)≥−0.15; and
 
   ( ln  η( T 1)− ln  η( T 2))/( T 1− T 2)<( ln  η( T 2)− ln  η( T 3))/( T 2− T 3), and
 
   wherein η(T 1 ) is the viscosity of the toner at 60° C., η(T 2 ) is the viscosity of the toner at 90° C., and η(T 3 ) is the viscosity of the toner at 130° C.   
     
     
         15 . An image forming apparatus comprising:
 an image holding means for holding an image;   a charging means for charging a surface of the image holding means;   an electrostatic image forming means for forming an electrostatic image on the charged surface of the image holding means;   a developing means for developing the electrostatic image formed on the surface of the image holding means with toner to thereby form a toner image;   a transfer means for transferring the toner image formed on the surface of the image holding means onto a surface of a recording medium;   a cleaning means for cleaning the surface of the image holding means; and   a fixing means for fixing the toner image transferred onto the surface of the recording medium,   wherein the cleaning means has a contact means for contacting the surface of the image holding means, the contact means having a JIS-A hardness of from 90° to 130° inclusive,   wherein the toner satisfies the following formulas:
   ( ln  η( T 1)− ln  η( T 2))/( T 1− T 2)≤−0.14;
 
   ( ln  η( T 2)−ln η( T 3))/( T 2− T 3)≥−0.15; and
 
   ( ln  η( T 1)− ln  η( T 2))/( T 1− T 2)<( ln  η( T 2)−ln η( T 3))/( T 2− T 3), and
 
   wherein η(T 1 ) is the viscosity of the toner at 60° C., η(T 2 ) is the viscosity of the toner at 90° C., and η(T 3 ) is the viscosity of the toner at 130° C.